1. Field of the Invention
The present invention relates a thermosetting adhesive material for connecting connection terminals provided on the opposing sides of a pair of opposing substrates.
2. Description of the Related Art
Electronic devices, primarily portable terminal devices and the like, have been getting lighter, thinner, shorter and smaller while incorporating high functions in recent years. Correspondingly mounting areas in these devices have become narrow. Consequently, the direct flip-chip mounting of bare IC chips on IC mounting substrates, and the working of the chips into the form of a chip-size package (CSP) are now being performed.
Such mounting generally involves the use of a thermosetting adhesive material in the form of a film, paste, or liquid, which contains a thermosetting resin such as an epoxy resin and a curing agent as its primary components, and which further contains electroconductive particles for anisotropic electroconductive connection as needed.
More recently, there have been attempts at reducing the coefficient of linear expansion of a cured adhesive material to bring this coefficient closer to that of the material being bonded (such as an IC chip or wiring substrate) by adding an insulating inorganic filler such as alumina or silica in order to enhance the connection reliability of a thermosetting adhesive material such as this.
If an insulating inorganic filler is simply added, however, there will be a drop in toughness parameters, such as a decrease in elongation or an increase in the elastic modulus of the cured adhesive material, which is a problem in that the connection reliability actually suffers.
It is an object of the present invention to solve the above problems encountered with prior art, and to be able to add an insulating inorganic filler to a thermosetting adhesive material for connecting connection terminals provided on the opposing sides of a pair of opposing substrates, without diminishing the toughness parameters of this material.
The inventors arrived at the present invention upon discovering that the stated object could be achieved by adjusting the elastic modulus of a cured thermosetting adhesive material so as to maintain a specific relationship with respect to the insulating inorganic filler content (vol %).
Specifically, the present invention provides a thermosetting adhesive material for connecting connection terminals provided on the opposing sides of a pair of opposing substrates, said thermosetting adhesive material containing a thermosetting resin and an insulating inorganic filler,
wherein the insulating inorganic filler content (a; vol %) and the elastic modulus of the thermosetting adhesive material after curing (E; GPa/30xc2x0 C.) satisfy the following relational formula (1):
0.042a+0.9 less than E less than 0.106a+2.5xe2x80x83xe2x80x83(1)
and at the same time, the insulating inorganic filler content (a; vol %) and the tensile elongation (d; %) at 25xc2x0 C. of the thermosetting adhesive material after curing satisfy the following relational formula (2).
xe2x88x920.072a+4 less than d less than xe2x88x920.263a+13xe2x80x83xe2x80x83(2)